A hybrid vehicle travels by drive force of one of a three-phase motor-generator (three-phase motor). The three-phase motor is controlled by a motor control apparatus in accordance with a vehicle operation condition. When a disconnection arises in three-phase power supply wires, which supply power to the three-phase motor, the motor control apparatus determines that the three-phase motor has an abnormality. The motor control apparatus interrupts a power conversion device connected to the three-phase motor thereby to prohibit the control operation of the three-phase motor (for example, JP 2001-69607A corresponding to U.S. Pat. No. 6,329,772).
In some hybrid vehicles, a three-phase motor is used to start an internal combustion engine. Specifically, when the internal combustion engine is started manually by operating a start key or automatically from an idle-stop condition, the three-phase motor is driven to start the internal combustion engine. In such a vehicle, when the internal combustion engine is stopped upon occurrence of a disconnection in three-phase power supply wires provided to supply electric power to the three-phase motor, the three-phase motor cannot be driven again even if a restarting of the internal combustion engine is tried. Thus the internal combustion engine cannot be started.
However, when the disconnection arises in the three-phase power supply wires, which supply power to the three-phase motor, a warning light is activated to indicate a malfunction. As a result, it is likely that the internal combustion engine will be stopped manually by a driver or automatically by the idle-stop operation. In such a case it is also likely that the internal combustion engine will be needed to be restarted.